Novel gonadal characteristics in an aged bovine freemartin

Anti-Müllerian hormone: A novel biomarker for detecting bovine freemartinism

The anti-Müllerian hormone (AMH) indicates ovarian reserve in cattle, maintaining a consistent trajectory post-puberty. In heterosexual pregnancies, the development of the Müllerian duct in female foetuses is inhibited, resulting in an anticipated minimal or absent ovarian reserve capacity. This investigation aimed to compare AMH levels in healthy Holstein heifers that had reached puberty with those of freemartin animals of the same breed and age. The study incorporated Holstein heifers reaching puberty between 11 and 15 months of age in Group 1 (G1, n = 20) and freemartin animals in Group 2 (G2, n = 19, 16). AMH measurements (AMH-1/AMH-2) were recorded at 12-day intervals for the study participants. Notably, AMH levels in three freemartin animals could not be detected, prompting statistical analysis based on measurements from the remaining 16 freemartin animals in G2. A statistically significant correlation was observed between two separate measurements in G1 and G2 (p < .001). Furthermore, AMH-1 and AMH-2 levels were statistically higher in G1 than in G2 (p < .001). In G1, AMH-1 levels ranged from 227 to 677 pg/mL, with an average of 367.3 ± 25.5 pg/mL, and AMH-2 levels ranged from 234 to 645 pg/mL, with an average of 380.8 ± 24.4 pg/mL. Conversely, in G2, AMH-1 levels ranged from 10 to 72 pg/mL, with an average of 26.8 ± 4.44 pg/mL, and AMH-2 levels ranged from 12 to 68 pg/mL, with an average of 28.75 ± 4.18 pg/mL. The mean AMH levels in G1 were approximately 14 times higher than in G2 (p < .001). Consequently, ROC analysis utilizing AMH-1 and AMH-2 data established cut-off values of ≤72 and ≤ 68 pg/mL respectively for distinguishing freemartin animals. In conclusion, AMH could be used as a reliable biomarker for identifying Holstein freemartin animals.

From Enrico Sertoli to freemartinism: the many phases of the master testis-determining cell†

Sertoli cells, first identified in the adult testis by Enrico Sertoli in the mid-nineteenth century, are known for their role in fostering male germ cell differentiation and production of mature sperm. It was not until the late twentieth century with the discovery of the testis-determining gene SRY that Sertoli cells' new function as the master regulator of testis formation and maleness was unveiled. Fetal Sertoli cells facilitate the establishment of seminiferous cords, induce appearance of androgen-producing Leydig cells, and cause regression of the female reproductive tracts. Originally thought be a terminally differentiated cell type, adult Sertoli cells, at least in the mouse, retain their plasticity and ability to transdifferentiate into the ovarian counterpart, granulosa cells. In this review, we capture the many phases of Sertoli cell differentiation from their fate specification in fetal life to fate maintenance in adulthood. We also introduce the discovery of a new phase of fetal Sertoli cell differentiation via autocrine/paracrine factors with the freemartin characteristics. There remains much to learn about this intriguing cell type that lay the foundation for the maleness.

Somatic cell fate maintenance in mouse fetal testes via autocrine/paracrine action of AMH and activin B

Fate determination and maintenance of fetal testes in most mammals occur cell autonomously as a result of the action of key transcription factors in Sertoli cells. However, the cases of freemartin, where an XX twin develops testis structures under the influence of an XY twin, imply that hormonal factor(s) from the XY embryo contribute to sex reversal of the XX twin. Here we show that in mouse XY embryos, Sertoli cell-derived anti-Mullerian hormone (AMH) and activin B together maintain Sertoli cell identity. Sertoli cells in the gonadal poles of XY embryos lacking both AMH and activin B transdifferentiate into their female counterpart granulosa cells, leading to ovotestis formation. The ovotestes remain to adulthood and produce both sperm and oocytes, although there are few of the former and the latter fail to mature. Finally, the ability of XY mice to masculinize ovaries is lost in the absence of these two factors. These results provide insight into fate maintenance of fetal testes through the action of putative freemartin factors.

Applying real-time quantitative PCR to diagnosis of freemartin in Holstein cattle by quantifying SRY gene: a comparison experiment

BACKGROUND

Freemartinism generally occurs in female offspring of dizygotic twins in a mixed-sex pregnancy. Most bovine heterosexual twin females are freemartins. However, about 10% of bovine heterosexual twin females are fertile. Farmers mostly cull bovine fertile heterosexual twin females due to the lack of a practical diagnostic approach. Culling of such animals results in economic and genetic-material losses both for dairy and beef industry.

METHODS

In this study, a comparative test, including qualitative detection of SRY gene by polymerase chain reaction (PCR), quantitative detection of relative content of SRY by real-time quantitative polymerase chain reaction (qPCR), and quantitative detection of H-Y antigen, was performed to establish the most accurate diagnosis for freemartin. Twelve Holstein heterosexual twin females were used in this study, while three normal Holstein bulls and three normal Holstein cows were used as a positive and negative control, respectively.

RESULTS

Polymerase chain reaction results revealed that SRY gene were absent in three heterosexual twin females and only two of them were verified as fertile in later age. The qPCR results showed that relative content of SRY was more than 14.2% in freemartins and below 0.41% in fertile heterosexual twin females. The H-Y antigen test showed no significant numerical difference between freemartin and fertile heterosexual twin female.

DISCUSSION

Our results show that relative content of SRY quantified by qPCR is a better detection method for diagnosis of freemartin in Holstein cattle as compare to qualitative detection of SRY gene by PCR or quantitative detection of H-Y antigen. To the authors' knowledge, this is the first time we applied qPCR to diagnosing freemartin by quantifying SRY gene and got relative SRY content of each freemartin and fertile heterosexual twin female. We concluded that low-level of SRY would not influence fertility of bovine heterosexual twin female.

Characterization of anti-Müllerian hormone in a case of bovine male pseudohermaphroditism

The current report aimed to characterize plasma anti-Müllerian hormone (AMH) in bovine male pseudohermaphroditism. The blood AMH concentration in a Japanese Black male pseudohermaphrodite calf was compared with pre- and post-pubertal male and female calves and castrated calves. The concentration in the case was higher than in post-pubertal males, castrated males, and pre- and post-pubertal female calves (p < .05), but similar to that in pre-pubertal male calves. After extraction of the testes, the concentration in the case dropped to a certain extent. The extracted testes expressed AMH, as detected by immunohistochemistry. This study is the first to show the characterization of AMH in a male pseudohermaphrodite calf. AMH levels in peripheral blood might be useful to diagnose male pseudohermaphroditism in cattle.